Did you import the presets using LR? If you do so, LR will put these to the correct locations.
On Windows it's right click / Import in the Presets Panel ... will be similar on a Mac.
Where are you storing the presets you have loaded/imported? Just move them from wherever they are now to that Preset folder displayed when going to Preferences>Presets tab>Show Lightroom Presets Folder.
On Windows it is in the Users\Username\AppData\Roaming\Adobe\Lightroom then there are several other folders in there.
On OS X the Pictures folder is in your Username folder.
I've discovered that the Local Adjustments presets don't go in the Picture>Lightroom folder on the Mac. Rather they go in this folder: User>Library>Application Support>Adobe>Lightroom>Local Adjustments.
And there's no way to have LR import them there. If you double click on them in the Finder Desktop, it will install them in the wrong place (the Picture>Lightroom path).
The default LR presets (Burn, Dodge, and 2 others) show up just fine on the pull-down menu in Local Adjustments bar and they are in the same folder with the newly acquired presets (about 20 of them) but the new ones won't appear in the pull-down menu. Have re-launched LR numerous times but still they don't show.